A hybrid vehicle is a vehicle on which a hybrid power system is provided. Such a hybrid system is a system in which two types of power sources, such as a gasoline engine and an electric motor, are combined and used.
Characteristics of the hybrid system lie in that the gasoline engine and the electric motor are selectively used in accordance with travel conditions of the vehicle and that advantages of each are used to compensate for weak points of the other.
Moreover, a hybrid vehicle using a gasoline engine and an electric motor together as the power sources can be operated using an engine having a smaller engine displacement than that of a comparable conventional vehicle (ICE) using the gasoline engine as the only power source.
Furthermore, in such a hybrid vehicle, the electric motor functions as a power generator during deceleration, and regenerative braking is performed by converting kinetic energy of the vehicle into electric energy when braking. This converted electric energy is stored in the battery and reused during acceleration and the like. Therefore, as the vehicle is operated the battery used in the hybrid vehicle is repeatedly discharged during the acceleration or the like and charged by the regenerative braking during the deceleration.
As the hybrid vehicle battery carried as the power source degrades over time during use, it thus has a finite service life. This occurs because, when the vehicle is operated for long periods of time, the inner resistance of the battery rises, and cell charge and discharge capabilities (battery capacity) gradually degrade. As such, it is imperative that accurate information on the state of the battery in the hybrid vehicle can be readily obtained.
Factors which influence the degradation of the battery over the elapse of time mainly include vehicle specifications data, battery environment, power consumption of electric components, and the traveling of the vehicle. The vehicle specification data is concerned with vehicle type and the like of the vehicle, and examples of such information include the vehicle model, the vehicle weight, and facility specifications. Here, facility specifications are, for example, types and capacities of the engine and electric components such as an air conditioner installed on the vehicle. The vehicle type and the facility specifications of the vehicle concern the power consumption of the battery of the vehicle, and are therefore factors which influence the degradation of the battery. The battery environment is the environment wherein the battery itself is disposed, and examples include temperature of the battery, atmospheric temperature, and humidity. Over-discharge and overcharge of the battery hasten degradation of the battery, and are therefore factors which influence degradation of the battery (battery life). Examples of the electric components which effect the power consumption include a power-consuming air conditioner or audio system installed on the vehicle. These electric components consume the power stored in the battery, and therefore they are factors which influence the degradation of power. Furthermore, vehicle travel is concerned with, for example, the travel distance and a driving operation of the vehicle. In general, because the degradation of the battery tends to increase with the distance traveled by the vehicle, vehicle travel is a factor which influences the degradation of the battery. The influence on the degree of the degradation of the battery also varies according to the driving habits of the vehicle operator.
Meanwhile, battery degradation can lead to collapse of the balance of optimum selective use of the gasoline engine and the electric motor, with the result that the burden on the gasoline engine increases. That is, deterioration of capability due to the degradation of the battery over time occurs in the electric motor which should originally function as the power source, and automatic control is performed so as to compensate for the capability deterioration by greater reliance on the gasoline engine. As a result, the vehicle travels with the engine having a smaller displacement as compared with the same type of conventional vehicle, so that a travel fuel consumption of the gasoline decreases.
This increase of fuel efficiency is more remarkable in driving including greater cornering, lane changes, and starting or stopping than in a drive pattern of traveling at a constant speed, that is, normal travel. This occurs because, owing to the combined use of the gasoline engine and the electric motor, the hybrid system more effectively uses the power source in a drive pattern including cornering, lane changes, and starting or stopping. On the other hand, during normal travel, the vehicle mainly travels under power of the gasoline engine, and hence the decrease in the travel fuel consumption is about the same as in the drive operation of the conventional vehicle. The characteristics of the hybrid system are such that the travel fuel consumption varies according to driving patterns, for example, travel speed or travel route of the vehicle, or the operation of the driver.
Moreover, with regard to the travel fuel consumption of the conventional hybrid vehicle, for example, an average fuel consumption, a momentary fuel consumption, a total fuel consumption, a past maximum fuel consumption, and the like may be measured and displayed. The display of these fuel consumption values begins when the ignition switch is turned on. For example, for the average fuel consumption and the momentary fuel consumption, an average fuel consumption for each minute and a momentary fuel consumption (over approximately 30 minutes) are displayed. In case of the total fuel consumption, a total fuel consumption from a data reset operation up to that point is displayed, and in case of the past maximum fuel consumption, the maximum value between reset operations of the total fuel consumption display is displayed.
On the other hand, an electric car battery display device for displaying information concerning the degradation of a battery is disclosed in Japanese Patent Application Laid-Open No. 10-4603, and a vehicle travel state display device for displaying information concerning fuel consumption is disclosed in Japanese Patent Application Laid-Open No. 2002-274219.
FIG. 11 shows an electric car battery display device as disclosed in Japanese Patent Application Laid-Open No. 10-4603. A display device 51 provided near the driver seat is constituted by a degradation display section 52 indicating a state in which the battery should be replaced and a charge display section 53 which displays information indicating whether or not the battery state is satisfactory. The degradation display section 52 has a display portion 54 divided into zones of a state G (green) in which the battery is not degraded, a state Y (yellow) in which it is advised that an inspection be made, a state R (red) in which battery replacement is advised, and a state E (a red lamp lights or blinks) in which the battery must be replaced, and an indicator 56 is positioned in a zone, depending on the state of the battery, to display the state of the battery degradation. The charge display section 53 has a display portion 55 divided into zones of a state G (green) indicating normal use and a state R (red) in which charging must be performed, and an indicator 57 is positioned in a zone, depending on the state of the charging, to display the state of the charging of the battery.
FIG. 12 shows a travel state display device of a vehicle as disclosed in Japanese Patent Application Laid-Open No. 2002-274219. In display means 60, a fuel consumption display section 61, an energy breakdown display section 62, and an accumulated energy display section 63 are displayed. In the fuel consumption display section 61, a kinetic energy correspondence fuel consumption 65 and a positional energy correspondence fuel consumption 66 are stacked on an apparent fuel consumption 64, and displayed as a bar graph. In the energy breakdown display section 62, breakdowns of absorption energy 67 by a brake and regeneration energy 68 by a motor are displayed as a bar graph. The accumulated energy display section 63 displays therein a total accumulated amount 69 of the kinetic energy and the positional energy, vertical bar graphs of an accumulated amount 70 of electric energy, and arrows 71, 72, 73 and 74 indicating states of the energy.